In _______ disorder, phenylalanine is accumulated and converted into phenyl pyruvic acid and other derivatives. Accumulation of these in brain results in mental retardation. These are also excreted through urine because of its poor absorption by kidney :-

Options

A. Alkaptonuria
B. Phenylketonuria
C. Sickle cell Anemia
D. Albinism

Answer

To solve the question regarding the disorder in which phenylalanine accumulates and is converted into phenylpyruvic acid, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Amino Acid**: The question mentions phenylalanine, which is an essential amino acid that normally gets converted into another amino acid called tyrosine.

**Hint**: Remember that phenylalanine is crucial for protein synthesis and is converted into tyrosine under normal conditions.

2. **Understand the Disorder**: In the disorder described, phenylalanine is not converted into tyrosine due to a deficiency in the enzyme phenylalanine hydroxylase. As a result, phenylalanine accumulates in the body.

**Hint**: Think about what happens when an enzyme is deficient or absent in a metabolic pathway.

3. **Conversion to Phenylpyruvic Acid**: The accumulated phenylalanine is then converted into phenylpyruvic acid and other derivatives. This accumulation can have toxic effects, particularly on the brain.

**Hint**: Consider the consequences of toxic accumulation of substances in the body, especially in the brain.

4. **Effects on the Brain**: The accumulation of phenylpyruvic acid in the brain leads to mental retardation and other neurological issues due to its toxic effects.

**Hint**: Reflect on how metabolic disorders can impact cognitive functions.

5. **Excretion in Urine**: The excess phenylalanine and its derivatives are poorly absorbed by the kidneys and are excreted in the urine, which is a key diagnostic feature of this disorder.

**Hint**: Think about how metabolic disorders can be diagnosed through urine tests.

6. **Name the Disorder**: The disorder characterized by the accumulation of phenylalanine and its conversion to phenylpyruvic acid is known as Phenylketonuria (PKU).

**Hint**: Recall that PKU is a classic example of an inborn error of metabolism.

### Final Answer:
The disorder is known as **Phenylketonuria (PKU)**.